MANKATO, Minn. -- Add Anthony Herrera to the growing list of offensive starters who have missed time in Minnesota Vikings training camp.

The right guard dropped out late in Saturday's morning practice, grimaced when he returned to the field as a spectator and didn't return for the night session.

"I think he may have had a back spasm or something like that," coach Brad Childress said between practices.

Herrera, 30, is coming off a season in which he struggled to regain strength after offseason shoulder surgery and missed two games with a concussion.

While Herrera's starting spot doesn't appear to be in doubt, rookie fifth-round pick Chris DeGeare -- who replaced Herrera with the No. 1 offense -- has been one of the standouts in camp and at least appears a good bet for a reserve role.

Before Saturday, DeGeare had gotten all his work at left guard, but Childress indicated earlier in the week he'd see time on the other side eventually.

"It may not be the most comfortable thing -- he is a natural right-hander," Childress said of DeGeare, a relative giant at 6-foot-4 and 335 pounds compared to Herrera (6-2, 315).

"But yeah, you've got to see those guys in there and see if they can flip it over in their brain, because when they get that battlefield position, you don't really care. If they're one of the seven guys up, they've got to go in and man a spot they're not used to."

Tight end Visanthe Shiancoe also sat out the night practice with an unknown injury, and no update was given on his status. That leaves tackles Bryant McKinnie and Phil Loadholt as the only offensive starters who haven't missed at least one full practice's worth of team drills.

Harvin back soon?

Receiver Percy Harvin missed a seventh consecutive day of practice while tending to the passing of his grandmother, but he could rejoin the team when practice resumes Monday.

"I'm expecting him here in the next couple days," Childress said.

No practice is scheduled Sunday -- the only off day during the two-week camp.

Health watch

Middle linebacker E.J. Henderson (leg) participated in live tackling drills for the first time in the morning session and gave coaches a minor scare when he got up slowly after whiffing on rookie running back Toby Gerhart. Henderson stayed in and finished the period, though.

Running back Adrian Peterson (leg) participated on a limited basis in team drills but was held out of higher-contact activities, including live tackling and one-on-ones. His role expanded in the evening, when there was no tackling.

Cornerback Benny Sapp (dehydration) was in pads for the first time in a week and participated in team drills, once laying out rookie receiver Marquis Hamilton after a catch.

• After a 90-minute rain delay in the morning, players took the field in full pads for the second time in camp. Practice included a 4-minute (chew-the-clock) period with live tackling.

• Gerhart had a rough go in one-on-one pass rush/pass block drills, getting whipped by LBs Chad Greenway (twice) and Erin Henderson before getting an extra turn and stopping LB Kenny Onatolu. RB Ian Johnson, a long to make the roster, was the strongest in the drill and also had a good one-on-one receiving rep against E.J. Henderson.

• Another rookie, RT Bill Noethlich, got burned once outside by third-string DE Michael Montgomery. On the second rep, both players ended up on the ground as teammates cackled. Noethlich -- a long shot out of Southwest Minnesota State -- also had a false start during the "live" 4-minute offense period.

• PK Rhys Lloyd hit 5 of 6 field-goal attempts, missing from 40 yards. His first attempt sailed over the fence surrounding the practice fields and a member of the team's emergency-support staff square in the face.

• Webb fumbled a snap during team drills -- at least the second time it's happened, after a similar play in Tuesday's goal-line period. "Some things he's got cold," Childress said. "But I just think every situation's a new situation, whether it's short-yardage where the ball goes on the ground on the goal line. He's a talented enough kid physically."